Connection Factory and Destination

A message-driven bean is a client to a Connector inbound resource adapter. The
message-driven bean container uses the JMS service integrated into the GlassFish Server for
message-driven beans that are JMS clients. JMS clients use JMS Connection Factory- and
Destination-administered objects. A JMS Connection Factory administered object is a resource manager Connection Factory
object that is used to create connections to the JMS provider.

The mdb-connection-factory element in the glassfish-ejb-jar.xml file for a message-driven bean specifies
the connection factory that creates the container connection to the JMS provider.

The jndi-name element of the ejb element in the glassfish-ejb-jar.xml file specifies the
JNDI name of the administered object for the JMS Queue or Topic
destination that is associated with the message-driven bean.

Message-Driven Bean Pool

The container manages a pool of message-driven beans for the concurrent processing of
a stream of messages. The glassfish-ejb-jar.xml file contains the elements that define the
pool (that is, the bean-pool element):

Domain-Level Settings

You can control the following domain-level message-driven bean settings in the EJB
container:

Initial and Minimum Pool Size

Specifies the initial and minimum number of beans maintained in the pool. The default is 0.

Maximum Pool Size

Specifies the maximum number of beans that can be created to satisfy client requests. The default is 32.

Pool Resize Quantity

Specifies the number of beans to be created if a request arrives when the pool is empty (subject to the Initial and Minimum Pool Size), or the number of beans to remove if idle for more than the Idle Timeout. The default is 8.

Idle Timeout

Specifies the maximum time in seconds that a bean can remain idle in the pool. After this amount of time, the bean is destroyed. The default is 600 (10 minutes). A value of 0 means a bean can remain idle indefinitely.

For information on monitoring message-driven beans, click the Help button in the Administration
Console. Select the Stand-Alone Instances component, select the instance from the table, and
select the Monitor tab. Or select the Clusters component, select the cluster from
the table, select the Instances tab, select the instance from the table, and
select the Monitor tab.

Message-Driven Bean Restrictions and Optimizations

Pool Tuning and Monitoring

The message-driven bean pool is also a pool of threads, with each message-driven
bean instance in the pool associating with a server session, and each server
session associating with a thread. Therefore, a large pool size also means a
high number of threads, which impacts performance and server resources.

When configuring message-driven bean pool properties, make sure to consider factors such as message
arrival rate and pattern, onMessage method processing time, overall server resources (threads, memory,
and so on), and any concurrency requirements and limitations from other resources that
the message-driven bean accesses.

When tuning performance and resource usage, make sure to consider potential JMS provider
properties for the connection factory used by the container (the mdb-connection-factory element
in the glassfish-ejb-jar.xml file). For example, you can tune the GlassFish Server Message
Queue flow control related properties for connection factory in situations where the message
incoming rate is much higher than max-pool-size can handle.

The onMessage Runtime Exception

Message-driven beans, like other well-behaved MessageListeners, should not, in general, throw runtime exceptions.
If a message-driven bean’s onMessage method encounters a system-level exception or error that
does not allow the method to successfully complete, the Enterprise JavaBeans Specification, v3.0
provides the following guidelines:

If the bean method encounters a runtime exception or error, it should simply propagate the error from the bean method to the container.

If the bean method performs an operation that results in a checked exception that the bean method cannot recover, the bean method should throw the javax.ejb.EJBException that wraps the original exception.

Any other unexpected error conditions should be reported using javax.ejb.EJBException (javax.ejb.EJBException is a subclass of java.lang.RuntimeException).

Under container-managed transaction demarcation, upon receiving a runtime exception from a message-driven bean’s
onMessage method, the container rolls back the container-started transaction and the message is redelivered.
This is because the message delivery itself is part of the container-started transaction.
By default, the GlassFish Server container closes the container’s connection to the JMS
provider when the first runtime exception is received from a message-driven bean instance’s
onMessage method. This avoids potential message redelivery looping and protects server resources if
the message-driven bean’s onMessage method continues misbehaving. To change this default container behavior,
use the cmt-max-runtime-exceptions property of the MDB container. Here is an example asadmin set
command that sets this property:

asadmin set server-config.mdb-container.property.cmt-max-runtime-exceptions="5"

The cmt-max-runtime-exceptions property specifies the maximum number of runtime exceptions allowed from a
message-driven bean’s onMessage method before the container starts to close the container’s connection
to the message source. By default this value is 1; -1 disables this
container protection.

A message-driven bean’s onMessage method can use the javax.jms.Message.getJMSRedelivered method to check whether a
received message is a redelivered message.